External Beam Radiation Therapy

Intensity Modulated Radiation Therapy, or IMRT, is the most advanced form of external beam radiation therapy. IMRT allows physicians to precisely target and deliver higher doses of radiation tailored for each patient and greatly reducing side effects. What makes this possible is IMRT's sophisticated treatment planning system. The planning system allows doctors to shape, or conform, several small radiation beams to the tumor while reducing radiation to healthy tissue. At Fox Chase, we combine MRI and CT scans and ultrasound to ensure the most precise delivery of radiation. IMRT is used to treat patients with prostate, breast, lung, cervical, endometrial and head and neck cancers.Fox Chase Cancer Center was the first in the region to use IMRT and our physicians have the most and longest experience with IMRT.

3-dimension conformal radiation therapy, or 3D-CRT, is similar to IMRT but may offer a better outcome for some types or locations of cancer. IMRT and 3D CRT utilize 3-dimensional imaging to aid in designing tailored treatment plans. And like IMRT, the radiation beams are shaped precisely to the tumor and treatment plans are tailored for each patient. However, depending on the circumstance of the cancer, 3D CRT may offer a better treatment approach than IMRT because there are fewer radiation beams, allowing doctors to completely avoid healthy tissue when appropriate. 3D CRT is used to treat certain patients with lung, gynecologic, gastrointestinal, bladder, and brain cancers.Fox Chase developed 3D CRT and pioneered its use in prostate cancer.

Stereotactic radiosurgery allows for the delivery of large doses of radiation in a very small area. Usually treatment is given in one treatment but can be administered over several sessions. Stereotactic radiosurgery involves aiming an x-ray or gamma-ray at a target or tumor. High doses can be directed at the target, while surrounding normal tissue receives much lower doses. Stereotactic radiosurgery is used to treat patients with primary or metastatic brain tumors and other intracranial cancers.Fox Chase was one of the first (if not the first) in the region to do extracranial SRS.

Stereotactic radiotherapy uses the same techniques as stereotactic radiosurgery, but is used to treat areas outside of the head and brain, usually the lungs. As with stereotactic radiosurgery, this technology allows radiation to be precisely delivered to its target. Because the beam is so precise, doctors can preserve more healthy tissue than with conventional external beam. Additional precision is achieved through use of rigid immobilization (holding the patient perfectly still) which benefits patients with tumors in the central nervous system and head and neck.

Image-guided radiation therapy uses imaging devices, such as X-rays, ultrasound and CT scans, to guide the daily radiation treatment. On-board imaging was developed to improve the precision and effectiveness of cancer treatments. It allows physicians to target and track tumors more accurately. The On-Board Imager provides image-guided radiation therapy (IGRT) by obtaining high-resolution X-ray images to pinpoint tumor sites, adjust patient positioning if necessary and complete a treatment, all within the time it would take to deliver standard treatment. IGRT can improve efficiency, precision and treatment outcomes. IGRT is often used in conjunction with CT-on-Rails and BAT ultrasound for prostate cancer patients. IGRT is also used to treat patients with certain lung and gynecologic cancers.Fox Chase was the first in the world to use BAT and piloted its use helping it become a routine part of treatment.

Dynamic multi-leaf collimator (DMLC) — Part of the linear accelerator, this device uses metal "leaves" to modulate the intensity of radiation beams. By visualizing the shape and location of the tumor, radiation oncologists can determine the required beam angles for treatment. Beam intensity is regulated by calculating the size of the space between the leaves and how long they remain open. This delivers a lethal dose to the tumor, while protecting nearby critical organs.

Stereotactic Radiosurgery (SRS) and Stereotactic Radiotherapy (SRT) offer physicians the opportunity to deliver large doses of radiation to very small areas by aiming an X-ray or gamma-ray at a target or tumor. Radiation can be precisely delivered to its target while preserving more healthy tissue than with conventional external beam therapy.

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